Endoglycan, a heparan-dermatan sulphate association, is a highly purified heparinoid extracted from porcine intestinal mucosa. The aim of our study was to investigate the fibrinolytic system in a group of healthy controls and vascular disease patients, before and after endoglycan administration "per os". All the patients had a reduced basal fibrinolytic activity. The tests carried out were PT, PTT, FDP, Euglobulin Lysis Time (ELT), fibrinogen, plasminogen, alpha 2-antiplasmin, alpha 2-macroglobulin and t-PA activity assayed with a chromogenic method. After endoglycan administration, we have shown a significant shortening of ELT with complete normalization during the treatment. A fibrinogen decrease and either plasminogen or alpha 2-antiplasmin increase was seen. This was shown in normals too, however to a lesser extent. During therapy most of the healthy subjects, but only some patients, showed increased t-PA levels. Before and during treatment, significantly higher t-PA levels were seen in the control group as compared to the patients group. Reduced t-PA release was seen in our vascular disease patients. In conclusion, endoglycan "per os" appears to exert a stimulatory effect on the fibrinolytic system.